This is an epidemiological investigation of antecedent factors of possible etiologic significance in bladder cancer among humans. Special attention is given to the artificial sweeteners, cyclamates and saccharin, whose use was increasing rapidly until the intervention of government restrictions. Other factors being studied include a variety of environmental toxins, occupational exposures and tobacco smoke. A minimum of about 375 patients with invasive cancer of the urinary bladder and an equal number of demographically similar controls are being sought in the metropolitan Baltimore area. After identification and verification of the pathological diagnosis, interviews in depth are conducted concerning the prior exposure of the respondents to artificial sweeteners as well as to other factors considered possible bladder carcinogens. In a later phase of the investigation, it is hoped to probe prior exposure to artificial sweeteners (as well as other potential bladder carcinogens) among patients with presumably benign bladder papillomas and control patients, as well as the relationship between such papillomas and bladder cancer.